More than 50% of male cancer patients subjected to cisplatin-based chemotherapy will suffer from long-term infertility. This is a significant concern because many of these patients are children or young men who survive their cancer and would hope to later reproduce. However, medical treatment for chemotherapy-induced infertility is not currently available. A key factor in the development of cisplatin-induced infertility is germ cell apoptosis, and activation of the proapoptotic mediators p53 and Nuclear Factor kappa B (NF?B) has been implicated in its development. Ghrelin, a novel hormone, has anti-apoptotic properties and suppresses NF?B in other tissues. Our preliminary studies indicate that it reduces cisplatin-induced apoptosis in germ cells. However, ghrelin's mechanism(s) of action in this setting and its effect on fertility are unknown. The long-term objectives of this application are: a) to develop new strategies for preserving fertility in individuals exposed to chemotherapeutic drugs and b) to establish the mechanisms mediating ghrelin's effects in this setting. Hypothesis: We hypothesize that ghrelin will prevent cisplatin-induced infertility and downregulate testicular NF?B and p53 activation induced by cisplatin. Our specific aims are: 1) To determine the effect of ghrelin administration on cisplatin-induced infertility and 2) To establish the effects of ghrelin and cisplatin on testicular p53 and NF?B activity. Design and methods: In our rodent model of cisplatin-induced gonadal damage we have observed that ghrelin prevents cisplatin-induced testicular apoptosis and NF?B activation. We are now proposing to test the effects of ghrelin and cisplatin on fertility, p53 and NF?B activity by exploiting a new transgenic mouse line that has been engineered to express luciferase and green fluorescent protein under control of a promoter that contains NF?B consensus binding sites. Based on the data generated in our adult model, we also will establish the feasibility of a prepubertal model of infertility. Significance: Fertility is the major life-style concern in more than 80% of children and men who are long-term survivors of cancer chemotherapy. Establishing the mechanisms and effects of ghrelin on fertility, germ cell apoptosis and NF?B and p53 activity in this setting will be important to develop methods to prevent or reverse the infertility caused by cisplatin and other chemotherapeutic agents. Such a pursuit will have relevance for maintaining long-term fertility in men who are exposed to chemotherapeutic agents, chemicals or radiation. PUBLIC HEALTH RELEVANCE: A significant proportion of children and men receiving chemotherapy for the treatment of cancer suffer damage to their reproductive organs leading to infertility. We currently do not have a way to prevent or predict who will become infertile after receiving chemotherapy;however, our preliminary work shows for the first time that a new hormone called "ghrelin" prevents this damage to the reproductive organs due to chemotherapy. The experiments we propose here will determine the effects of ghrelin on fertility and will lead us to the development of new ways to prevent or treat infertility.